PLT 1 describes a technique for displaying the photographing range of a camera. According to the technique described in PLT 1, when the location of a camera and the like are designated on a top view shown within a predetermined area in a display device, the display device shows a horizontal view in this top view and a vertical view in an elevation view. The horizontal view is the projection of the photographing range of the camera; the vertical view is a field of view of the camera in a vertical plane to the horizontal surface and contains the optical axis of the camera. FIG. 21 is a schematic view illustrating a horizontal view and a vertical view shown by the technique described in PLT 1.
According to the technique described in PLT 1, for example, when the location of a camera is designated on a top view 100, a camera indicator 101 representing the camera appears on the top view 100. Then, a user adjusts the height of the camera by dragging a camera indicator 111 shown on an elevation view 107. After the location of the camera is designated, a calculated horizontal view 105 and vertical view 115 appear on the top view 100 and an elevation view 107, respectively. The vertical view 115 contains an optical axis 110 of the camera. If the icon of a person is dragged and dropped onto the top view 100, a person indicator 102 appears at this location, and a person indicator 112 also appears in the elevation view 107. Likewise, if the location of a wall as an obstacle of the camera is designated, a wall indicator 103 appears on the top view. In FIG. 21, the person indicator in the top view 100 is denoted by the letter symbol “102”; the person indicator in the elevation view 107 is denoted by the letter symbol “112.”
The technique described in PLT 1 provides the relationship between the field of view of a camera and a wall, a person or the like in a predetermined area by creating the above displays. This relationship will be used to adjust the location of the camera.